[PATCH v2] drm: rcar-du: Fix leak of CMM platform device reference

[Jacopo Mondi]

Hi Laurent,

On Wed, Dec 16, 2020 at 04:08:36PM +0200, Laurent Pinchart wrote:
> The device references acquired by of_find_device_by_node() are not
> released by the driver. Fix this by registering a cleanup action.
>
> Fixes: 8de707aeb452 ("drm: rcar-du: kms: Initialize CMM instances")
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
> ---
> Changes since v1:
>
> - Only set rcdu->cmms[] if the CMM config option is enabled
> - Use platform_device_put()
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> index 92dfa3d4c011..fdb8a0d127ad 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -14,6 +14,7 @@
>  #include <drm/drm_fb_cma_helper.h>
>  #include <drm/drm_gem_cma_helper.h>
>  #include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_managed.h>
>  #include <drm/drm_probe_helper.h>
>  #include <drm/drm_vblank.h>
>
> @@ -726,8 +727,12 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
>  		 * disabled: return 0 and let the DU continue probing.
>  		 */
>  		ret = rcar_cmm_init(pdev);
> -		if (ret)
> +		if (ret) {
> +			platform_device_put(pdev);
>  			return ret == -ENODEV ? 0 : ret;
> +		}
> +
> +		rcdu->cmms[i] = pdev;
>
>  		/*
>  		 * Enforce suspend/resume ordering by making the CMM a provider

Sorry but don't we have an error path here below too, and if it fails
-EINVAL is returned and the whole modeset_init() bails out without
having put the platform device.

> @@ -739,13 +744,20 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
>  				"Failed to create device link to CMM%u\n", i);
>  			return -EINVAL;
>  		}
> -
> -		rcdu->cmms[i] = pdev;
>  	}
>
>  	return 0;
>  }
>
> +static void rcar_du_modeset_cleanup(struct drm_device *dev, void *res)
> +{
> +	struct rcar_du_device *rcdu = to_rcar_du_device(dev);
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i)
> +		platform_device_put(rcdu->cmms[i]);
> +}
> +
>  int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  {
>  	static const unsigned int mmio_offsets[] = {
> @@ -766,6 +778,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
>  	if (ret)
>  		return ret;
>
> +	ret = drmm_add_action(&rcdu->ddev, rcar_du_modeset_cleanup, NULL);
> +	if (ret)
> +		return ret;
> +
>  	dev->mode_config.min_width = 0;
>  	dev->mode_config.min_height = 0;
>  	dev->mode_config.normalize_zpos = true;
> --
> Regards,
>
> Laurent Pinchart
>